.clearfix::after {
  content: '';
  display: block;
  clear: both;
}

@media screen and (min-width: 1190px) {
  header {
    width: 1190px;
    margin: 0 auto;
  }

  .mobile-nav-btn {
    display: none;
  }
}

@media screen and (min-width: 960px) and (max-width: 1189px) {
  header {
    width: 1000px;
    margin: 0 auto;
  }

  .mobile-nav-btn {
    display: none;
  }
}

@media screen and (min-width: 768px) and (max-width: 959px) {
  header {
    width: 800px;
    margin: 0 auto;
  }

  .mobile-nav-btn {
    display: none;
  }
}


@media screen and (min-width: 480px) and (max-width: 767px) {
  header {
    width: 100%;
    margin: 0 auto;
  }

  .nav-list {
    display: none;
  }
}

@media screen and (max-width: 479px) {
  header {
    width: 100%;
    margin: 0 auto;
  }

  .nav-list {
    display: none;
  }
}

@media screen and (max-width: 330px) {

  header,
  footer {
    width: 300px !important;
    margin: 0 auto;
  }

  .nav-list {
    display: none;
  }
}



header .nav-list {
  width: 100%;
  height: 50px;
  background-color: #fff;
  margin-bottom: 1rem;
  border-bottom: 1px solid #ddd;
  text-align: center;
}

header .mobile-nav-list {
  padding: 10px;
}

header .mobile-nav-list.open {
  height: 200px;
  opacity: 1;
  transition: all .3s linear;
}

header .mobile-nav-list.close {
  height: 0;
  opacity: 0;
  transition: all .3s linear;
}

header .mobile-nav-list .list-item {
  padding: 5px;
  border-bottom: 1px solid #ddd;
}

header .mobile-nav-btn {
  width: 100%;
  padding: 0 10px;
  height: 44px;
  border-bottom: 1px solid #ddd;
}

header .mobile-nav-btn .iconfont {
  font-size: 28px;
  line-height: 44px;
}


header .nav-list .list-item {
  position: relative;
  float: left;
  margin-left: 20px;
  padding: 0 10px;
  line-height: 50px;
  cursor: pointer;
}

header .nav-list .list-item:first-child {
  margin-left: 0;
}

header .nav-list .list-item .tips {
  display: none;
  position: absolute;
  left: 15px;
  bottom: -35px;
  width: 150px;
  height: 30px;
  text-align: center;
  line-height: 30px;
  font-size: 12px;
  background-color: #fff;
  border-radius: 8px;
}

header .nav-list .list-item .tips::before {
  content: '';
  display: block;
  position: absolute;
  top: -10px;
  left: 10px;
  width: 0;
  height: 0;
  border: 5px solid transparent;
  border-bottom-color: #ddd;
}

header .nav-list .list-item .underline {
  position: absolute;
  width: 0;
  height: 2px;
  left: 0;
  bottom: -2px;
  background-color: #f00;
  /* 在原本元素上再加一个transition */
  transition: all .3s linear;
}


header .nav-list .list-item .changeBtn label:hover {
  cursor: pointer;
}

header .nav-list .list-item:hover .underline {
  width: 100%;
  transition: 0.45s;
}

header .nav-list .list-item:hover .tips {
  display: block;
  transition: all 0.5s linear;
  background-color: #ddd;
}

footer {
  margin: 0 auto;
  width: 100%;
  padding: 1rem 0;
  text-align: center;
}

footer div {
  margin: 3px;
  font-size: 13px;
  color: #000;
}

footer div a {
  color: #000;
}